1. Field of the Invention
The present invention generally relates to the field of attachments for eyeglasses. More particularly, the present invention relates to the field of clip-on optical element attachments to be clipped on in front of the lenses of eyeglasses or like.
2. Description of the Prior Art
Generally, prior art clip-on eyeglass devices are well known in the art. These clip-on eyeglass devices have not been entirely satisfactory for several reasons. For example, eyeglasses are made in a variety of sizes and a variety of configurations. The configuration of eyeglasses tends to vary from time to time because of changes in fashion or for other reasons. Many prior art clip-on devices are mass produced in one size and shape. Specifically, the optical elements of such devices often do not have the same configuration and spacing as the lenses of eyeglasses with which they are used. Undersized optical elements and optical elements that are out of register with the eyeglass lenses tend to disrupt the wearer's field of view and also present an unaesthetic appearance to others. Oversized optical elements may contact the wearer's skin in an irritating manner and have projecting edges that may promote dislodgement of the accessory from the eyeglasses.
To avoid these problems, some manufacturers of eyeglass frames provide clip-on sunglass devices having optical elements that conform with the lenses and lens spacings of a particular frame. Prior art conforming clip-on devices are largely limited to use with specific frame configuration for which the device was designed or at best are suitable for use with a limited number of frames that have closely similar configurations. Dispensing opticians typically offer a variety of different frame styles and stocking of a corresponding large inventory of different clip-on devices is costly and inefficient.
The following two (2) prior art patents are found to be pertinent to the field of the present invention:
1. U.S. Pat. No. 4,842,399 issued to Tsai on Jun. 27, 1989 for "Apparatus And Method For Retaining A Spectacle Lens On A Rimless Spectacle Frame With A Tough Cord" (hereafter the "Tsai Patent"); and
2. U.S. Pat. No. 5,123,724 issued to Salk on Jun. 23, 1992 for "Customized Clip-On Eyeglass Accessory And Method Of Manufacture" (hereafter the "Salk Patent").
The Tsai Patent discloses an apparatus and method for retaining a spectacle lens on a rimless spectacle frame with a tough cord. It comprises a rimless frame, a spectacle lens, and a tough cord. The frame has an inverted U-shaped portion formed in its inward surface with an open-ended lens receiving slot for engaging with the upper peripheral portion of the lens. Each end of the inverted U-shaped portion has a counterbore formed therethrough. The cord extends through two counterbores in the inverted U-shaped portion and is integrally formed with two enlarged end portions which are confined within the large-diameter outer end portion counterbores respectively. One of the interengaging surfaces between the lens and the cord has a slot so that they can be engaged with each other, thereby retaining the lens on the frame with cord.
The Salk Patent discloses a customized clip-on eyeglass accessory and method of manufacture. An outline of the lens regions of a particular pair of eyeglasses is prepared and two initially oversized optical elements are trimmed to conform with the outline. Upper and lower eyeglass engaging clasps are secured to each optical element and ends of a resilient bridge member are inserted into passages in each upper clasp. At least one upper clasp and the optical element to which it is fastened is slidable along the bridge member to space the elements apart at a distance corresponding to the spacing of the eyeglass lens regions. The upper clasps are then secured to the bridge member and end portions of the bridge member that protrude from the upper clasps are then cut off.
It is desirable to provide a very efficient and also very effective design and construction of an improved clip-on optical element device which can conform to any size and shape of a particular eyeglass frame configuration. It is also desirable to provide an improved clip-on optical element device with the capability of rapidly changing the frame configuration to meet the need of a particular frame configuration.